Dyeing basic nitrogenous fibers by the metachrome process with chromable azo dyes having nitrogen free substituents ortho to the azo group



Aug. 22, 1950 c. A. AMICK ETAL 2,520,080 DYEING BASIC NITROGENOUS FIBERSBY THE METACHROME PROCESS WITH CHROMABLE AZO DYES HAVING NITROGEN FREESUBSTITUENTS ORIHO TO THE AZO GROUP 4 Sheets-Sheet 2.

Filed July 18, 1947 CONTROL By HEN/F) LSD/V,

ATTORNEY Aug. 22, 1950 Filed July 18, 1947 c. A. AMICK ETAL 2,520,080DYEING BASIC NITROGENOUS FIBERS BY THE METACHROME PROCESS WITH CHROMABLEAZO DYES HAVING NITROGEN FREE SUBSTITUENTS ORTHO TO THE AZO GROUP 4Sheets-Sheet 5 CONT/POL.

r ATTORNEY Aug. 22, 1950 c. A. AMICK ETAL 2,520,030

DYEING BASIC NITROGENOUS FIBERS BY THE METACHROME PROCESS WITH CHROMABLEAZO DYES HAVING NITROGEN FREE SUBSTITUENTS ORTHO TO THE AZO GROUP FiledJuly 18, 1947 4 Sheets-Sheet 4 GOA 714 04 .20

Patented Aug. 22, 1950 DYEING BASIC NITROGENOUS FIBERS BY. THEMETACHROME. PROCESS WITH 'CHR'OMABL'E A'ZO DYES HAVING. N ITRJO- GEN'SUBSTETUENTS ORTHO TO THE AZO GROUP Chester A. Amick andWillardIH..Watkins-,.Bound Brook, andHenry- E. Millson, Plainfield, NHL.assignors to- American *Cyanamid Company, New York, N. 1 acorporation-of Maine Application July 18, 1947, Serial No. 761,983

15 Claims.

This invention relates to improvements in the metachrome dyeingprocesswith chromable azo dyes having nitrogen freev metallizable groupsortho tovtlie. azozgroupz In: the past, fibers such: as Wool, silk,synthetic fibers of. similar: type. from: casein, polyamides andthelikehaveabeen dyedby the metachrome process in which the dyestuif anda mordant containing a chromium compound have been present in thedyebath. In the dyeing procedure the dye is. affixed to-thefiber and ismetallized. There have" been many. disadvantages to the metachromedyeing process. For example, dye penetration has sometimes been:inadequate because of. premature reaction withthe chromium in themordant; Thus dyes which donotpenetrate all of the fibers or aredestroyed during thedyeing operation, particularly in the case of heavyshades, have been considered unsuitable for use in the metachromeprocess and have required resort to a process starting out with thepreformed metallized dye or with a top or bottom chome process. Azodyestuffs having only hydroxyl groups ortho to the azo group have notgiven as good results in the metachrome process and'have beenconsidered'less suitable for dyeing by that process.

Numerous attempts have been made to increase the penetration ofthe dyesand obtain stronger dyeings. One of the earlier attempts involved theuse of cationic surface active agents; This process, however, did notachieve practical success because although greatly increased penetrationsometimes resulted there was reaction between the surface active agentand the colored constituents of thedye' bath to produce a coloredprecipitate; scum orflocs. These-larger colored aggregates" oftencausedserious spots or-flocs in the" dyeing and precluded practical use ofthis method. The next development which was practica'llyusefulinvolved'the addition to-the metachrome dyebat-h' of both cationic andnonionic surface activeagents, the latter serving to keep the reactionproducts of the cationic agent and colored constituents in fineddispersion. This process forms the-subject matter of the application ofMillson and Royer, Serial No.- 420;504'; filed November 26, 194-1, nowabandoned.

It was later found by Boyer and Amick (application Seria'l'No. 542,445,filed June 27jl944, now Eat'ent' 2-;4341-78) that if thecationicagentwas 2. colloidize'd, either alone or in conjunction with the chromablecolor or-the mordant, increased penetration and level dyeing could beobtained without. the presence of a-nonionic surface active agent.

In our earlier application, ,Ser'. No; 750,886., filed May 27, 1947, Wehave: described and claimed a metachrome process inwhich the colloidizedcationic surface active agent is associated with the-other features. Thefirst is the presencelofa salt of an alkaline earth metalsuch'asmagnesium sulfate and secondly a procedure in which the dye bathinitially has'a pH sufiiciently high so that rapid chromation isprevented or retarded and the pH is, then progressively lowered: untilfinal cromation results.

According to the present invention we have found that with certainchromable azo dyes, namely those which do not have a nitrogen containinggroup ortho to the azo. group, a marked increase in color strength isobtained if the, alkaline earth metal salt and initial high pH followedby a reduced pH is used without any cationic surface active agent. Thealkaline earth metal salt in the present case as in the earlierapplication above referred to must of course have an anion which doesnot form complexes with chromium containing salts. The increase instrength is marked and there is no problem of scum formation. It is thuspossible to obtain strengths which do not compare unfavorably with thoseobtained by the process of the copending application above referred towithout requiring any cationic agent and hence encountering no problemof colored scum or floc formation.

It is not known why marked increase in strength is obtainable with thparticular chromable azo dyes of the present invention without anycationic surface active agent. Many chromable colors of other types donot show any in? crease in strength unless a cationic surface activeagent is used. It is not known whether the mechanism of dyeing withthese particular azo dyes is different than that which occurs with someother chromable colors or whether theim proved result without a cationicsurface active agent is due to other factors- It is, therefore,.notdesired to limit the present invention to any theory of dyeingmechanism.

The invention will be described in. conjunction 3 with the specificexamples and in connection with the drawings in which:

Figs. 1 to 9 are pairs of curves drawn by a recording spectrophotometershowing dyeing strengths with and without the presence of variousalkaline earth metal salts. The parts are by weight.

Example 1 A dye bath was prepared comprising 2% of the dye having ColorIndex 203, 10% ammonium sulfate and 1% potassium bichromate in 400 ml.of distilled water. A -gram woolen piece or skein, pre-wet withdistilled water, is entered into the dye bath which is gradually heatedto the boil in about 30 minutes. The bath is then boiled for about 30minutes, after which the volume of water is replenished and 2% aceticacid is added. Boiling is continued for another 30 minutes, the watervolume again replenished and 4% of 28% acetic acid is added. Boiling isagain continued for about 30 minutes after which the dyed wool isremoved from the bath, rinsed in distilled water, squeezed and dried.During th dyeing the wool is turned intermittently to insure uniformdyeing. All percentages are based on the weight of the wool. This is thecontrol dyeing and the procedure used is one that is often recom--mended for dyeing chromable colors by the metachrome process.

A second dye bath is prepared comprising 2% of the dye having ColorIndex 203, 2% ammonium hydroxide, 340% magnesium sulfate containing 7molecules of water of crystallization and 0.6% potassium bichromate in400 m1. of distilled water. A 5-gram wool sample is entered into thisbath and dyed as above. The color value of the wool sample dyed by thisprocedure is 322% compared to 100% for th control, both measurementsbeing made on a recording spectrophotometer as shown in Fig. 1.

Example 2 The procedure of Example 1 is repeated exactly except calciumnitrate is substituted for the magnesium sulfate of Example 1. As willbe seen from Fig. 2 the value of the dyeing made from the bathcontaining the calcium nitrate was 187%,,

compared to 100% for the control.

Ezcample 3 The procedure of Example 1 is repeated exactly except themagnesium sulfate is replaced with barium chloride. As Will be seen fromFig. 3, the color value of this dyeing is 321%, compared to 100% for thecontrol dyeing.

Example 4 The procedure of Example 1 is repeated exactly except themagnesium sulfate is replaced by strontium salicylate. The color valuefor the dyeing of the wool made in this bath as obtained by the G. E.recording spectrophotometer is 226% as will be seen in Fig, 4. Thiscompares with 100% for the control dyeing.

Example 5 Example 7 The procedure of Example 1 is repeated exactlyexcept the dye is made by coupling diazotized 2-amino-4-nitrophenol to4-sulfo beta naphthol. The color value of the wool dyed in the magnesiumsulfate bath is 120% compared to for the control dyeing as will be seenin Fig. '7.

Example 8 The procedure of Example 1 is repeated exactly except the dyehaving Color Index 652 is used instead of the dye having Color Index203. The color value of the wool dyed in the bath containing themagnesium sulfate is about 133% compared to 100% for the control as willbe seen in Fig. 8.

Example 9 The procedure of Example 1 is repeated exactly except thedyeings are made on synthetic protein fiber from casein instead of wool.If the color value of the control dyeing is 100%, then th color value ofthe dyeing made from the dye bath containing the ammoniacal solution ofmagnesium salt is about 111%.

Example 10 The procedure of the preceding example is repeated exactlyexcept the material dyed is silk instead of synthetic protein fiber fromcasein. If the color value of the control dyeing is 100% then the valueof the dyeing obtained from the dye bath containing the ammonia andmagnesium salt is about Example 11 'The procedure of the precedingexample is repeated except the dyeings are made on nylon instead ofsilk. If the color value of the control dyeing is 100%, the value of thedyeing made from the dyebath containing the ammonia and magnesiumsulfate is about 196 The comparison curves drawn by a recordingspectrophotometer appear in Figure 9.

We claim:

1. A method of dyeing which comprises subjecting substantiallyunmetallized basic nitrogenous fibers to the action of a dye bath formedby mixing a chromable azo dye having nitrogen-free groups ortho to theazo group, a soluble alkaline earth metal salt the anion of which doesnot form complexes with chromium containing salts, a soluble chromiumcontaining compound, water, and sufiicient alkali to make the bathalkaline and to cause said dye to react with said alkaline earth metalsalt to form an alkaline earth metal complex of said dye andinsufiicient to materially damage said fibers, partially dyeing saidfibers from said complex at an elevated temperature, gradually loweringthe pH of said bath to a point where decomposition of said complex andchromation of the dye take place, and completing the dyeing at saidlowered pH.

2. A method of dyeing which comprises subjecting substantiallyunmetallized basic nitrogenous fibers to the action of a dye bath formedby mixing a chromable azo dye having nitrogen-free groups ortho to theazo group, magnesium sulfate, a soluble chromium containing compound,water, and sufiicient alkali to make the bath alkaline and to cause saiddye to react with said alkaline earth metal salt to form an alkalineearth metal complex of said dye and insuflicient to materially damagesaid fibers, partially dyeing said fibers from said complex at anelevated temperature, gradually lowering the pH of said bath to a pointwhere decomposition of said complex and chromation of the dye takeplace, and completing the dyeing at said lowered pH.

3. A method of dyeing which comprises subjecting wool fibers to theaction of a dye bath formed by mixing a chromable azo dye havingnitrogen-free groups ortho to the azo group, a soluble alkaline earthmetal salt the anion of which does not form complexes with chromiumcontaining salts, a soluble chromium containing compound, water, andsufiicient alkali to make the bath alkaline and to cause said dye toreact with said alkaline earth metal salt to form an alkaline earthmetal complex of said dye and insuflicient to materially damage saidfibers, partially dyeing said fibers from said complex at an elevatedtemperature, gradually lowering the pH of said bath to a point wheredecomposition of said complex and chromation of the dye take place, andcompleting the dyeing at said lowered pH.

4. A method of dyeing which comprises subjecting wool fibers to theaction of a dye bath formed by mixing a chromable azo dye havingnitrogen-free groups ortho to the azo group, magnesium sulfate, asoluble chromium containing compound, water, and sufiicient alkali tomake the bath alkaline and to cause said dye to react with said alkalineearth metal salt to form an alkaline earth metal complex of said dye andinsufiicient to materially damage said fibers, partially dyeing saidfibers from said complex at an elevated temperature, gradually loweringthe pH of said bath to a point where decomposition of said complex andchromation of the dye take place, and completing the dyeing at saidlowered pH.

5. A method of dyeing which comprises subjecting wool fibers to theaction of a dye bath formed by mixing a chromable azo dye havingnitrogen-free groups ortho to the azo group, a soluble alkaline earthmetal salt the anion of which does not form complexes with chromiumcontaining salts, a soluble chromium containing compound, water, andsuflicient alkali to make the bath alkaline, but with a pH not greaterthan 9.5, and to cause said dye to react with said alkaline earth metalsalt to form an alkaline earth metal complex of said dye andinsufilcient to materially damage said fibers, partially dyeing saidfibers from said complex at an elevated temperature, gradually loweringthe pH of said bath to a point where decomposition of said complex andchromation of the dye take place, and completing the dyeing at saidlowered pH.

6. A method of dyeing which comprises subjecting wool fibers to theaction of a dye bath formed by mixing a chromable azo dye havingnitrogen-free groups ortho to the azo group, magnesium sulfate, asoluble chromium containing compound, water, and suificient alkali tomake the bath alkaline, but with a pH not greater than 9.5, and to causesaid dye to react with said alkaline earth metal salt to form analkaline earth metal complex of said dye and insufiicient to materiallydamage said fibers, partially dyeing said fibers from said complex at anelevated temperature, gradually lowering the of said bath to a pointwhere decomposition of said compleX and chromation of the dye takeplace, and completing the dyeing at said lowered pH.

'7. A method according to claim 5 in which the azo dyestufi has theformula I SOaH 8. A method according to claim 5 in which the azo dye isdye No. 203 of the color index.

9. A method according to claim 5 in which the azo dye is dye No. 652 ofthe color index.

10. A method according to claim 1 in which the pH of the dye bath islowered by the addition of successive small portions of acid.

11. A method according to claim 2 in which the pH of the dye bath islowered by the addition of successive small portions of acid.

12. A method according to claim 3 in which the pH of the dye bath islowered by the additions of successive small portions of acid.

13. A method according to claim 4 in which the pH of the dye bath islowered by the additions of successive small portions of acid.

14. A method according to claim 5 in which the pH of the dye bath islowered by additions of successive small portions of acid.

15. A method according to claim 6 in which the pH of the dye bath islowered by the additions of successive small portions of acid.

CHESTER A. AMICK. WILLARD H. WATKINS. HENRY E. MILLSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

OTHER REFERENCES Application of Dyestuffs, by J. M. Matthews, publishedin New York by John Wiley & Sons, 1920, pages 356-358.

Metachrome Method of Dyeing, by C. H. A. Schmitt, article in Amer. Dyes.Rep. for June 26,

1939, pages P336-P341.

Theory and Practice of Wool Dyeing, by C. L. Bird, published 1947 inLondon by Society of Dyers and Colourists, pages 87, 88.

Application of Coal Tar Dyestuffs, by C. M. Whittaker, published 1919 inLondon by Bailliere, Tindall and Cox, pages 59, 60, 61.

1. A METHOD OF DYEING WHICH COMPRISES SUBJECTING SUBSTANTIALLYUNMETALLIZED BASIC NITROGENOUS FIBERS TO THE ACTION OF A DYE BATH FORMEDBY MIXING A CHROMABLE AZO DYE HAVING NITROGEN-FREE GROUPS ORTHO TO THEAZO GROUP, A SOLUBLE ALKALINE EARTH METAL SALT THE ANION OF WHICH DOESNOT FORM COMPLEXES WITH CHROMIUM CONTAINING SALTS, A SOLUBLE CHROMIUMCONTAINING COMPOUND, WATER, AND SUFFICIENT ALKALI TO MAKE THE BATHALKALINE AND TO CAUSE SAID DYE TO REACT WITH SAID ALKALINE EARTH METALSALT TO FORM AN ALKALINE EARTH METAL COMPLEX OF SAID DYE ANDINSUFFICIENT TO MATERIALLY DAMAGE SAID FIBERS PARTIALLY DYEING SAIDFIBERS FROM SAID COMPLEX AT AN ELEVATED TEMPERATURE, GRADUALLY LOWERINGTHE PH OF SAID BATH TO A POINT WHERE DECOMPOSITION OF SAID COMPLEX ANDCHROMATION OF THE DYE TAKE PLACE, AND COMPLETING THE DYEING AT SAIDLOWERED PH.